Electrical connector plug



Jwiwl, 1944.

R. w. CARLISLE Erm. 2,339,147

ELECTRICAL CONNECTOR PLUG Original Filed July 18, 1940 SHU INVENTORS Q W. CA QL /54 E MASTRODOAE 3 www A 7mm/vnf Patented Jee. 11, 1944 ELECTRICAL CONNECTOR PLUG Richard W. Carlisle, Elmsford, and Alfred J. Mastropoie, New York, N. Y., assignors to Sonotone Corporation, Elmsford, N. Y., a corporation of New York Original application July 18, 1940, Serial No. 346,112. Divided and this application May 16, 1942, Serial No. 443,278

2 Claims. (Cl. 173-269) This application is a division of our application Serial No. 346,112, led July 18, 1940.

This invention relates to electrical connector plugs, and particularly to electrical connector plugs for devices, such ashearing aid devices, which are formed of several operating units that have to be small enough for inconspicuous wear on the body of the user and have to be interconnected by electrical cords for completing the operating circuits between the several units.

Among the objects of the invention is an improved electrical connector plug of the foregoing type which is extremely small and is mechanically as well as electrically superior to prior connector plugs suitable for such applications.

The foregoing and other objects of the invention will be best understood from the following description of exempliilcatlons thereof, reference being had to the accompanying drawing wherein Fig. l illustrates a hearing aid earphone worn in the ear of the user equipped with a connector plug of the invention;

Fig. 2 illustrates a wall portion oi' the earphone of Fig. 1 equipped with a connector plug of the invention;

Figs. 3 to 5 are partially elevational and partially sectional views illustrating successive steps in mounting the connector plug of Figs. 1 and 2 on its cord;

Fig. f6 is an elevational view of a cord end with the completed plug mounted thereon. f

Most of the'deafened are very sensitive and seek to conceal their hearing impairment. Accordingly, va. satisfactory hearing aid device for supplying the deaiened person with the sound energy required to overcome his handicap must n be suitable for comfortable andlnconspicuous weer and simple and foolproof in operation so as to free the user from physical as well as mental strains. All the elements'of the device must not only be small and light in weight, but must be able to respond at high efilciency to all imi portant speech frequencies and they must operate satisfactorily under all conditions of use, without special attention and frequent reconditioning.

A most important lconsideration in the design oi' hearing aids is that they be as inconspicuous and as comfortable as possible. For instance, the midget earphone or receiver forming a part of such hearing aid has to be made extremely small so as to make it possible tohcld vit nush within the lobe of the ear in the way shown in Fig. 1. This requires that its thickness should notbe more than .3 ot an inch and that 'its diameter should be .8 of an inch or less.

Accordingly, the connector cord which completes the circuit between such earphone and the other elements of the hearing aid should be very thin and flexible, and it must be so connected to the earphone as to withstand the strain imposed thereon when the user pulls the cord. Furthermore, since such cords deteriorate and become unsanitary in use, they should be readily exchangeable. Accordingly, a detachable circuit connection must be provided between such cords and the elements of the hearing aid to which they are connected.

Many eiiorts have been made in the past to devise an electrical connector plug suitable for use in suchmidget earphones, and similar hearing aid elements. The electrical connector plug of the invention is of much simpler construction than the best prior 'electrical connector plugs used in similar applications and embodies various desirable novel features which facilitate the manufacture and assembly of such plugs and which make it possible to render them much more compact.

Although the electrical 4connector plug of the invention has many other applicationsoutside the hearing aid eld, it will be described in connection with its application to a midget earphone forming part of a hearing aid.

As shown in Fig. 1, such midget earphone 20 is worn either directly within' the lobe of the ear or on an ear tip molded to flt the ear, in` the way shown in our lcopending application Serial No. 334,678, filed May 11, 1940.

As shown in Figs. 1 and 2, such earphone'coxn-` prises an electromechanical driving transducer structure, enclosed in a tiny casing 2i and energized through cord leads 22 with electric speech frequency oscillations lso as to deliver acoustic energy through the loutlet duct of the knob 2l 4to the airin the ear canal of the user.

The circuit between the energizing leads 2l -of the driving structure 2i to the cord leads 22 hearing aid, it is essential that the detachable y connector plugs, which complete its operating circuits, shall assure good electrical circuit connections and at the same time shall be mechanically strong so as to withstand the strain to maintain the contact engagement and connection with suiiicient mech'anical force to prevent breaking of the contact engagement by the forces to which the lead is exposed in the course of ordinary use.

Figs. 2 to 6 show an improved construction and arrangement of one form of a plug and plug-cord connection of the invention which' makes it possible to reduce the bulk of the plug to a fraction of the best prior plugs, and protects the junction between the cord and the plug against damage incident to bending the cord relatively to the plug, while at the same time assuring a good mechanical and electrical connection .between the conducting portion of the cord lead and the plug as well as good external appearance of the cord plug connection.

The body of the plug 21 from which the shank 29 extends is of generally cylindrical form and has a cavity 3i in which the end of the cord lead 22 is h'eld after it is first prepared in the way shown in Fig. 3. In preparing the cord lead 22, a rectangular piece of sheet metal 32 is folded over a portion of the lead and clamped thereover, the sheet metal clip 32 having punched therein holes 33 so as to provide gripping projections which grip the exterior surface of the lead cover 34. Y

Such flexible cord lead is usually composed of a core consisting of a plurality of intertwisted flexible tinsel-like filaments 35 of highly conducting material, such as copper, and the core is covered by the covering 34 of flexible insulating material, such as suitably woven silk threads, arranged to thoroughly protect the conducting core and at the same time carry the strain imposed on the leads when it is being pulled in use.

The clip 32 is clamped a short distance, about 1/8 of an inch, from th'e end of the lead. The portion of the insulation covering 84 which extends beyond the end of the clip 32 is th'en stripped oi, as by a razor, so as to expose filaments 35 of tinsel in the way shown in FiglfB. The tinsel filaments 35 are then folded over the exterior of the conducting metallic clip 32 and inserted within the cavity 3| of th'e plug body 21. Thereupon, the rear portion of the cylindrical plug member 21 is placed in a tool formed, for instance, of two clinching members 36 while the plug is being rotated so as to deform the end portion of the cylindrical plug cavity into an annular groove while at the same time giving the edge portion 31 of the cavity walls an outward taper, in the way shown in Fig. 4. This construction assures that a Very intimate and good electrical connection as well as a positive mechanical gripping l connection is established between all the elements of the cord lead and the body of the plug, while at the same time giving the exterior of the plug cavity member a finished appearance which protects the junction of the cord lead to the plug and also prevents imposition of4 excessive strain on the cord when it is bent relatively to the plug.

and the clamping stress is distributed along the entire length of the cord lead which' is clamped within the clip 32. In addition, the tinsel is firmly clasped between the clip and the interior cylindrical surface of the plug cavity, thus securing a good electrical connection.

By forming the clamping groove 38 in the cord Junction cavity of the plug, the cavity Wall of the plug is automatically given an outwardly tapering semi-conical opening which eliminates any tendency to impose cutting stresses on the cord covering at the pointwhere it leaves the plug cavity. i

In the plug arrangement described above, each part of the connector plug is proportioned to carry a large, but safe, stress. Each portion performs at least one necessary function and in some cases several simultaneous functions. At the same time, all connector elements are made extremely small and compact. For instance, in the practical construction of such plug connectors, the largest outer diameter of the plug may be made as little as .080 of an inch or less while assuring a good mechanical and highly conducting electrical connection between the cord lead and the plug.

Various other modifications of the invention will suggest themselves to those skilled in the art. It is accordingly desired that in construing the breadth of the appended claims they shall not bel limited to the specific details shown and described in connection with the exemplications of the invention.

We claim:

l. In a detachable connector for a terminal end of a flexible electric lead comprising a ilexible insulating cover and a flexible conducting core having an exposed end portion extending beyond the end portion of said cover, a clip of relatively flexible sheet metal clamped around the end portion of said cover, the exposed end portion of said core being folded over the exterior of said clip, an integral elongated solid conducting plug memberhaving an exposed contact surface and an open tubular portion confining a longitudinal cavity at its inward end surrounding and engaging the exterior of said clip andthe end portions of said core folded over said clip, said tubular` portion of the plug member having a peripheral clamping region which is deformed in a radially inward direction in a uniform manner to a i sufficient inward depth as to inwardly deform the underlying portion of said clip and. compress the end portion of said coverfor establishing clamping engagement between the interior surface of said cavity and the exterior of said clip and the end portions of said core folded over said clip, said peripheral region extending sufficiently near the end'region of said cavity and being so deformed as to give the inner surfaces of said end region an outwardly tapered configuration.

2. In a detachable connector for a terminal end of a flexible electric lead comprising a ilexible insulating cover and a fiexible'conducting core having an exposed end port/ion extending beyond the end portion of said cover,.aclip of relatively flexible sheet metal clamped around the end portion of said. cover, the exposed end portion of said c ore"being folded over the exterior of said clip, Van integral elongated solid conducting plug member having an exposed contact surface and The groove 38 formed near the edge of the cylindrical cavity portion of the plug member 21 imparts to the plug a permanent deformation,

ing the exterior of said clip and the end portions of said core folded over said clip, a peripheral region oi said tubular portion of the plug member being deformed into a continuous inwardlyextending clamping groove which extends in a radially-inward direction, in a uniform manner. to a sumcient inward depth as to inwardly deform the underlying portion of said clip and compress the end portion of said cover for establishing clamping engagement between the interior surface of said cavity and the exterior of said clip and the end portions of said core folded over said clip, said peripheral region extending sumciently near the end region of said cavity and being so deformed as to give the inner surfaces of said end region an outwardly tapered contiguration.

' RICHARD W. CARLISLE.

ALFRED J. MABTROPOLE. 

